Fluid logic control system

ABSTRACT

A fluid logic control system for controlling the operation of, for example, industrial machines. The system includes a plurality of fluid-operated components, each of which includes a casing having a chamber, a movable spool in the chamber, ports in the casing, and passageways in the spool. The components include: a fluid logic gate capable of performing any one of the four logic functions: AND, OR, NOT, NOR ; a multiple pole relay; a differential pressure relay; a micro-valve differential pressure relay; a pilot light; a selector switch; and a push button relay. The spools are self-sealing and the casings are interchangeable.

United States Patent Dickason [451 May 9, 197 2 541 FLUID LOGIC CONTROLSYSTEM 3,092,143 6/1963 Denman ..l37/624. 14 [72] Inventor: Ronald KmckmnNewark NY. 3,305,211 2/1967 Phillips ..25l/368 X [73] Assignee:Garlock, Inc., Palmyra, N.Y. Primary Examiner-Henry T. Klinksiek [22]Filed: Jan. 12 1970 Attorney-Schovee & Boston [21] Appl. No.: 1,996 [57]ABSTRACT -A fluid logic control system for controlling the operation of,[52] LS. CL ME, for example industrial machines The ystem includes a 1137/596 rality of fluid-operated components, each of which includes a[51] hilt. Cl. ..F16k casing h i a h be a mo able pool in the chamber,[58] Field of Search ..l37/81.5, 624.14, 608, 561, ports in the casing,and passageways in the SPOOL The 137/596 552-5; 251/368 367; 235/201ponents include: a fluid logic gate capable of performing any R f endone of the four logic functions: AND, OR, NOT, NOR a mu]- e erences ltiple pole relay; a differential pressure relay; a microvalve dif-UNITED STATES PATENTS ferential pressure relay; a pilot light; aselector switch; and a push button relay. The spools are self-sealingand the casings 2,904,070 9/1959 Lynott ..137/552.5 areinterchangeab1e3,541,991 11/1970 Hartman.... ..235/201 X 3,057,551 10/1962 Etter..137/81.5 X

20 Claims, 22 Drawing Figures PATENTEDMAY 9 I972 8.661 166 vINVENTORRONALD K. DICKASON BY XaM r- KW ATTORNEYS PATENTEDMAY 9 I912 3.661.166

SHEET 3 [IF 6 FlG. IO

' INVENTOR RONALD K. DICKASON ATTORNEYS PAIENTEDMAY 91972 3.661.166

sum u 0F 6 FIG. [2 RKY UJI FIG. I3

INVENTOR. RONALD K. DICKASON XMPKW ATTORNEYS PATENTEDMAY 9M2 I 3,661,166

SHEET 5 0F 6 FIQ l8 INVENTOR.

RONALD K. DICKASON ATTORNEYS 1 FLUID LOGIC CONTROL SYSTEM BACKGROUND OFTHE INVENTION 1. Field of the Invention The,present invention relates-toa system of-machine bontrol and more particularly to a fluid logiccontrol system.

'2."Description of the Prior Art Fluid type controls areknown and areused in various applications in-industry because they havevarious'advantages over electrical and electronic controls. Some of themajor ad vantages of fluid control systems are that they'are: ('1) lessexpensive toinstall; (2) less expensive to maintain; (3) more dependable(a particular component can average being 100 times more dependable thanits electrical counterpart); (4) safer (there is no-chanceof electricalShOCk'fIOlTI a short-circuit); (5) simpler and easier to understand; and(6) they allow the use of pure circuits (pneumatic-hydraulic) throughoutthe entire system.

Two major approaches to fluid-type controls have been taken. Oneapproach is the use of pure fluidics-and-the second approach is the useof fluid logic control. The present invention relates to the realm offluid logiccontrol, however, it will be useful by way of backgroundinformation to briefly mention the field of pure fluidics. Pure fluidicsincludes the use of devices such as fluid amplifiers using'the Coandaeffect-(wall attachment) or laminar flow, as in turbulence amplifiers;such devicesuse very low fluid pressure (V4 to l psig) and low flow.These devices areof the non-moving parts type'and are very durable,however, they are difficult to manufacture and to use because, forexample, they require very close tolerances and the components within agiven system must be matched as to characteristics. Pure fluidicssystems do not carry enough energy to directly control a system. Theymust be used with a transforming valve having moving parts, before usecan be made of the signal in a pure fluidics controlsystem. Thedependability or durability of the pure fluidics system, therefore, isno better than that of the transforming valve.

The fluid logic control approach on the other hand, to which field thepresent invention relates, employs simple fluid logic elements, similarto control valves that have been available to the industry for years,with some, special logic elements (AND, OR, NOT, NOR) added thereto. Inmost cases, the components in this type of system have only one movingpart, and they are therefore very dependable. Such components are simpleand'easy to'manufacture and to maintain and service.

SUMMARY OF THE PRESENT INVENTION A fluid logic control system forcontrolling machine operations and including a plurality of componentsusing self-sealing spools and interchangeable casings. The systemincludes; a logic gate capable of performing any one of the four logicfunctions: AND, OR, NOT, NOR; a multiple pole relay; differentialpressure relays; a pilot light; a selector switch; and a push buttonrelay.

BRIEF DESCRIPTION OF THE DRAWINGS The above and additional objects andadvantages of the present invention will be more fully understood byreference to the following detailed description when read in conjunctionwith the attached drawings, wherein like reference numerals refer tolike elements and wherein:

FIG. 1 is an exploded view of a logic gate of the'present invention;

FIG. 2 is a perspective view of the logic gate of FIG. 1;

FIG. 3 is a vertical, cross-sectional side view through the logic gateof FIGS. 1 and 2;

FIGS. 4A, 4B, 4C, and 4D, are top plan views of the logic gate of FIGS.1-3 with the cover off showing the spools 16 and 18 in each of theirfour possible combinations of positions;

FIG. 5 is a top plan view of the cover of the logic gate of FIGS. 1-4showing the ports therein and providing an identification system forreferring to the various ports;

FIGS. 6' through 9 aretop plan views schematically showing the logicgate of FIGS. 1-5 hooked up to provide-the-AND, OR, NOT, NOR logicfunctions, respectively;

. FIG. 10 is an exploded view of a multiple pole relay according to thepresent invention; and

FIGS. 11 and 12 are perspective and cross sectional side views,respective of the multiplepole relay of FIG. 10;

FIG. 13 is a top plan view of the cover ofthe relay of FIG. 10 providingan identification system for referring to 'the va'rious ports therein; 7

FIG. 14is a cross-sectional view through a differential pressure relayaccording tothe present invention;

FIG. 15 is a cross-sectional view through a micro-valv'e'differentialpressure relay according to the present invention;

FIG. 16 is a cross-sectional view through a;pilot'lig ht"according tothe present invention; 7

FIG. "is a cross-sectional view through a selector switch according tothe present invention;

FIG. 18 is a cross-sectional view through a push button relay accordingto the present invention; and

FIG. 19 is a schematic, partly cross-sectional, circuit dia= gram of afluid logic control system using various components of the presentinvention. 7

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FLUID LOGIC GATE 1'0 7The structure of the fluid logic gate 10 is fully described in detailbelow. It is believed that a preliminary outline of the highlights ofits operation, using reference numerals developed below, will be helpfulto the reader prior 'to his I reference to the following detaileddescription of the structure. Referring to FIGS. l-9, the logic gate 10is to be connected in a fluid logic control circuit of a machineor'sys'ter'n' being controlled. Information as to the occurrence ornotibfa particular event is fed into the gate 10 by way of air 'lines84,

86, 88, and 90. This information is translated, in the gate 1'0, v

into various positions of the two spools 16 and IS; the spools 16 and 18can exist in any one of the four positionssho'wn iii forced intopredetermined locations in gate 10 by and in responseto the occurrenceof predetermined events in the operation of the machine. When suchevents occur, gate I0 produces a signal and this signal can be used toeffect some ad= ditional control of the operation of the machine beingcontrolled.

The present invention is in a fluid logic control system which system iscapable of using any of a great variety of fluids such as air, nitrogen,and many liquids. Since it is presently.

preferred that air be used, the following detailed description willspecify air as the operating fluid, but it is to be understood that thepresent invention is in no way limited to use with air. The air controlpressure used can be from 10 to psig. and is preferably 20 psig.

Referring now in detail to the drawings, FIGS. 1 through 9 illustrate afluid logic gate 10, constructed according to the present invention, andcomprising a casing 12 having aeentral cavity or chamber 14 in which arepositioned a pair er separate, unconnected movable spools l6 and 18. Theunconnectedis hereby defined to mean that the spools are" not connectedtogether by means of a spring positioned therebetween. Referring to theexploded view in FIG. I,- the casing 12 comprises a block 20 havingacentral opening" 22 therein, a cover 24, and a bottom plate 26. Thebottom piste 26 is completely imperforate, while the cover 24 is manufaetured with 22 holes or ports therein. In manufacture, the spools l6 and18 are placed in chamber 14 and the cover 24 and bottom plate 26 arethen permanently sealed to the block 20 (as by gluing).

In order to identify a particular port in cover 24, reference is made toFIG. showing a top plan view of cover 24. Twenty of the ports arearranged in a regular (as contrasted to an irregular or haphazard)rectangular array of four rows (A-D) and five columns (1-5). Any portcan thus be identified by a reference consisting of one letter A-Dfollowed by one numeral 1-5. In addition to these ports are two endports 28 and 30. All of the 20 ports A-l through D-5, plus ports 28 and30, are open to the chamber 14. The block 20 includes a pair of endpassageways 32 and 34 semi-circular in horizontal cross section), whichextent downwardly from top surface 35 of block 20 only part-way throughthe thickness of block 20. One side of each passageway 32 and 34 is opento chamber 14. The passageways 32 and 34 are aligned with ports 28 and30 in cover 24.

The same casing 12 is used in another embodiment of the invention (seeFIGS. 10-13). Certain of the ports are used in this embodiment andcertain are used in the embodiment of FIGS. 10-13. Further, in thisembodiment, different sets ofthe ports A-l to D-S are used dependingupon which logic function is to be performed. It is desirable tomanufacture the cover 24 with all 22 of the ports; those ports that arenot being used in any particular operation (those shown in dotted linesin the drawings) may be plugged up or simply left open, unless they areso positioned that operating fluid could leak out. It is to beunderstood that it is also possible to only drill (or otherwise provide)those ports that are to be used for the particular operation. When thenon-used ports are plugged, this can be done by, for example, gluing inplugs (not shown) similar to pins 68 and 70, but without the conical endthereof, so that the plugs do not interfere with the movement of thespools.

The-two spools l6 and 18 are identical and comprise L- shaped membershaving main rectangular portions 36 and 38 respectively, andright-angled arm extensions 40 and 42, respectively integral with mainportions 36-and 38 and adjacent the outer ends 44 and 46 respectively ofthe spools 16 and 18. Each of the spools l6 and 18 is provided with asingle, transverse, elongated groove 48 and 50 respectively, in itsupper surface 52 and 54 respectively. Each of the grooves 48 and 50 hasa width substantially equal to the diameter of the ports A1 to D-5 andhas a length substantially equal to (1) the center-to-center distanceseparating two adjacent ports in a column plus (2) the diameter of aport. The ports can be spaced apart in the rows the same distance asthey are in the columns, although this is not necessary.

Each of the top edges 55 and 57 of the inner ends 56 and 58 respectivelyof spools l6 and 18, respectively, are beveled, preferably at a angle,as shown in FIGS. 1 and 3. The inside top edges 60 and 62 of the armextensions 40 and 42 respectively, are similarly beveled for receivingstop pins 68 and 70 as described more fully hereinafter. Each of theouter ends 44 and 46 includes a groove 64 and 66 respectively. Thegrooves 64 and 66 communicate with passageways 32 and 34, respectively,so that when air is introduced through the passageway 32, for example,the air will fill the groove 64 to allow the air pressure to act over arelatively large area. This provides for a fast, positive response ormovement of the spool 16 upon introducing air pressure into the chamber14 through port 28.

With the spools l6 and 18 positioned in the chamber 14 with theorientation shown in FIG. 1, the cover 24 and bottom plate 26 arepermanently sealed to block 20. A pair of stop pins 68 and 70 (see FIG.3) are permanently positioned in ports C-1 and B-5 respectively. Eachpin includes an enlarged head 72 and 74 respectively, and a tapered orconical end 76 and 78 respectively; the taper is preferably at 45. Asshown in FIG. 3, the pins 68 and 70 operate to limit the inward extentof travel of the spools 16 and 18. For example, spool 16 can travel fromits outermost position adjacent end 80 (FIG. 4A)

of chamber 14, to its innermost position shown in FIGS. 3 and 4A,wherein pin68 abuts beveled edge 60 and pin simultaneously abuts bevelededge 55 of spool 16. Similarly, spool 18 can travel from its outermostposition adjacent end 82 (FIG. 4A) of chamber 14 to its innermostposition shown in FIG. 3, wherein pin 68 abuts beveled edge 57 and pin70 abuts beveled edge 62 of spool 18.

Spool 16 is forced to move inwardly when air pressure is introduced intochamber 14 through line 84, port 28, passageway 32 and groove 64.Similarly, spool 18 is forced to move inwardly by air pressureintroduced into chamber 14 through line 86, port 30, passageway 34 andgroove 66. Both spools 16 and 18 are forced to move outwardly at thesame time by air pressure introduced into chamber 14 through either portD-1 and line 88 or port A-5 and line 90.

Referring now to FIG. 4, the spools 16 and 18 are two-position spools;they each occupy one of two positions. FIG. 4A shows both spools 16 and18 in their innermost position; FIG. 4B shows both spools l6 and 18 inthe outermost position; FIG. 4C shows spool 18 in its innermost positionand spool 16 in its outermost position; and FIG. 4D shows spool 18 inits outermost position and spool 16 in its innermost position.

When spool 16 is in its outermost position, the groove 48 is in registerwith, and provides fluid communication between, ports A-2 and B-2. Whenspool 16 is in its innermost position, the groove 48 is in register withand provides fluid communication between, the two ports A-3 and B-3.Similarly, when spool 18 is in its outermost position, groove 50 is inregister with and provides fluid communication between the two ports C-4and D-4. When spool 18 is in its innermost position, groove 50 is inregister with, and provides fluid communication between, ports C-3 andD-3.

The logic gate 10 can be hooked up in such a way as to perform any oneof the four logic functions, AND, OR, NOT, NOR. In each case the portsA-I, B-l, C-2, D-2, A-4, B-4, C-5, and D-5 are plugged up (these portsare shown by dotted lines in the drawings). Ports C-1 and B-5 areplugged with stop pins 68 and 70 respectively. Further, depending onwhich of the four logic functions a particular gate 10 is to perform,additional ones of the ports may also be plugged, as will be pointed outbelow, with respect to each such logic function. Those ports that arenot involved in the operation of the gate 10 when used for a particularpurpose can either be left open or can be plugged. In some instances,certain ports should be plugged to prevent leakage of the operatingfluid therefrom.

Throughout the following discussion there will be four different airpressure inputs capable of moving one or more of the spools 16 and 18.These inputs are connected to the gate- 10 through input lines 84, 86,88 and 90, connected to ports 28, 30, D-l, and A-5, respectively. Also,there will be an input line 92 supplying air pressure for the outputresponse signal, which output signal will be transmitted through outputline 94. In essence, the gate 10 will be hooked up in a fluid logiccontrol circuit as an integral part thereof and will be receivinginformation from other components of the control circuit as to thefunctioning of the machine or system being controlled, the informationbeing introduced as air pressure via inputs 84, 86, 88 and 90. Dependingupon how the gate 10 v is hooked up, as a set of events occur, theinformation fed into the gate 10 will be reflected by the position ofthe spools l6 and 18. An output signal may or may not be produced atline 94. When an output signal is generated, it can be used to providesome portion of the overall control of the machine or system, as will beunderstood by those skilled in the art.

AND

The AND logic function of gate 10 will now be described with referenceto FIG. 6. In this use of gate 10,'the following ports may be closed orplugged up (these are in addition to those specified above): A-2, B-2,C-4, and D-4. A jumper line 96 (an air pressure conduit similar to lines84, 86, 88 and 90, for example), is connected between ports B-3 and'C-3to provide fluid communication therebetween. A slight bias pressure(about l0 psig, enough to move the spools l6 and 18) is provided atlines 88 and/or 90. It is noted that, alternatively, the circuit cancall for the use of a larger than bias pressure at 88 and/or 90. Now,given air inputs in lines 84 and86 (we will assume throughout thisdiscussion that an input is provided at line 92, of course), continuitythrough the gate will be provided from input 92 to output 94, thusproviding an output signal. An AND logic device produces an outputsignal only upon the simultaneous occurrence of two inputs (84 and 86).What occurs inside of gate 10 is that both spools 16 and 18 are forcedto move inwardly due to the air pressure introduced at 84 and 86; thisresults in groove 48 connecting ports A3, and B-3, and groove 50connecting ports C-3 and D-3, thus providing fluid continuity betweeninput 92 and output 94. It is to be understood that the abovearrangement of gate 10 to provide the AND logic function is not the onlymanner. in which the gate 10 can be used to provide the AND function.

The OR logic function of gate 10 will now be described with reference toFIG. 7. In this use of gate 10, the following ports may be closed orplugged up (in addition to those specified above regarding the genericuse of cover 24 for a logic gate 10): A-'-2, B-2, C-4, and D-4 (it isnoted that these are the same ports closed to provide the AND logicfunction). The input line 92 is connected to the two ports B-3 and C-3,while the output 94 is connected to the two ports A3 and D-3. A biaspressure is applied at lines 88 and/or 90 as described above. Now, givenan input at either 84 or 86, continuity through the gate 10 will beprovided from input 92 to output 94, thus providing an output signal. AnOR logic device produces an output response upon the occurrence of anyone of several inputs. Thus, the introduction of air pressure into gate10 through either input 84 or 86 will move either of the spools l6 and18 respectively to itsinnermost position thus providing fluidcommunication, via one of grooves 48 and 50, respectively, between theinput 92 and output 94.

NOT

The NOT logic function of gate 10 will now be described with referenceto FIG. 8. In this use of gate 10, the following ports may be closed orplugged up (in addition to those specified above that are plugged up incover 24, when cover 24 is used in a logic gate): A-3, B-3, C-3, andD-3. A jumper line 98 is connected between ports B-2 and C-4 to providefluid communication therebetween. A slight bias pressure (about 10 psig,enough to move the spools 16 and 18) is provided at lines 88 and/or 90.Now, given no input at either 84 or 86, continuity through the gate 10will be provided from input 92 to output 94, thus providing an outputsignal.

A NOT logic device produces an output response only when there are noinputs (84 or 86). What occurs inside of gate 10 given no inputs at 84or 86 is that both spools 16 and 18 are forced to move to theiroutermost positions due to the slight bias pressure provided at inputs88 and/or 90. This results in groove 48 providing fluid communicationbetween ports A-2 and B-2. and groove 50 providing fluid communicationbetween ports 04 and D4, thus providing continuity from input line 92through jumper line 98 to output line 94.

NOR

The NOR logic function of gate 10 will now be described with referenceto FIG. 9. In this application of gate 10, the same ports may be pluggedup as were plugged up in the NOT application described immediatelyabove; There are no jumper lines in the NOR application of gate 10,however, the input line 92 is connected to the two ports B-2 and C4, andthe output line 94 is connected to the two ports A-2 and D4. As in theNOT application described above, a slight bias air pressure is providedat lines 88 and 90. An output signal is obtained at output line 94 ifthere is no input signal at either one of lines 84 or 86. Thus, with noinput at (and regardlessof whether there is an input at 86), spool 16would be at its outermost position providing fluid communication betweenports A-2 and B-2, and this occurrence would produce an output signal 94through groove 48. Similarly, no input at 86 would also provide anoutput signal in output line 94 by providing fluid communication betweenports C-4 and D4. If either one of these events occur, i.e. no input at84 (and no input at 86, an output signal will be produced at output line94.

In the above discussion, it is noted that preferably a bias .of about 10psig is employed at lines 88 and 90 along with an operating pressure ofabout 20 psig at lines 84 and 86, so that the spools l6 and 18automatically will resume a predetermined normal position when an inputis released i.e. vented to atmosphere). It will be understood, ofcourse, that the logic gate 10 can be used for only one of the abovefour logic functions at any one time. The bottom plate 26 can have thesame ports as does cover plate 24 and the spools 16 and 18can havegrooves on their bottom faces so that one gate 10 can be used for twodifferent logic functions from the same inputs, if desired.

The block 20, cover 24 and the two bottom'plates 26 are preferablyinjection molded of a plastic material such as Delrin, a trademark ofduPont for a thermoplastic acetal resin material that is a polymerizedformaldehyde derivative. The spools 16 and 18 are preferably molded ofGylon," a trademark of Garlock, Inc. for a fibrous filled fluorocarbonplastic. The spools 16and 18 are preferably self-sealing andselflubricating in the chamber 14. Other materials can be used as willbe discussed more fully below.

MULTIPLE POLE RELAY I00 FIGS. l0l3 show a multiple pole relay 1000f thepresent invention. Since the relay employs the same casing 12' as doesthe logic gate 10 of FIGS. l-9, thesame reference numerals used todescribe the casing 12 of gate 10 will be used here, but with a prime,for simplicity of description.

The relay 100 comprises a casing 12', which can be identical to casing12 of the logic gate 10, except that ports C-1' and B-5' are not pluggedwith pins 68 and 70. The relay 100, however, does not employ the twospools 16 and 18 0f the logic gate 10 but rather employs a single spool102. The spool 102 comprises a rectangular block 104 provided with agrove 106 in one end 108 and a groove 110 in the other end 111 of spool102. Grooves 106 and 110 communicate with passageways 32 and 34 andserve to allow the operating fluid (such as air) to spread over arelatively large area of the end wall of the spool for the same reasonsdescribed above with respect to grooves 64 and 66 of spools 16 and 18 inFIG. 1. Spool 102 has twelve elongated, longitudinal grooves 112-123positioned in the top surface 124 of spool 102 and arranged in arectangular array containing four rows and three columns. Each of thefour rows of grooves is in register with one of the four rows of ports(Al' to D'5') in the cover 24'. Each of the grooves has a widthsubstantially equal to the diameter of any of the ports A-1 to D'5 and alength substantially equal to (l) the center-to-center distanceseparating two adjacent ports in a row, plus (2) the diameter of a port.The ports Al' to D-5 are equally spaced in each row and the ports arealso equally spaced in each column. The spacing in the rows ispreferably identical to the spacing in the columns, however, this is notessential.

The grooves 112-123 provide fluid communication between different onesof the ports, as will be described below, depending upon the positionthe spool 102 occupies in the chamber 14'.

The spool 102 moves back and forth in the chamber 14' and alwaysoccupies one of the two possible end positions therein,

102 in a first position abutting end wall 126. In this position, groove116, for example, provides fluid communication between ports A'-2 andA3. When the spool 102 is caused to move to its second position abuttingend wall 128, groove 116 will provide fluid communication between portsA3 and A'-4.

The spool 102 is caused to move by air pressure exerted through feedlines (not shown) connected to ports 28' and 30'. Various informationconcerning the operation of the machine being controlled is thenavailable by properly hooking up fluid lines to the ports A-l to D'5'.All or part of the ports can be used; the unused ports can be plugged(temporarily or permanently).

The spool 102 has a thickness and a width slightly greater than thecorresponding dimensions of the chamber 14' such that spool 102 isself-sealing in the chamber 14'.

An example of how relay 100 can be hooked up in a fluid logic controlcircuit with other embodiments of the present invention, to control theoperation of a machine, will be described below with respect to FIG. 19.

DIFFERENTIAL PRESSURE RELAY 130 FIG. 14 shows a differential pressurerelay 130 embodiment of the present invention. The purpose of thedifferential pressure relay 130 is to provide fluid communicationbetween two lines (202 and 204) when a certain condition occurs in theoperation of the machine being controlled and to not provide fluidcommunication between lines 202 and 204 when such condition does notexist. This embodiment of the invention mechanically senses when someportion of the machine occupies a particular position; in thisembodiment of FIG. 14 the position is that immediately adjacent therelay itself. The relay 210 of FIG. is similar to relay 130 of FIG. 14;the difference being that relay 210 of FIG. 15 can sense said positionat a point remote from the relay itself.

There are various ways in which the relay 130 can be arranged in a fluidlogic control circuit to provide some measure of the overall control ofthe machine being controlled. One possible way is shown in the schematiccircuit of FIG. 19.

Referring now in detail to the differential pressure relay 130 of FIG.14, the relay 130 comprises a casing 132 having a chamber 134 and aspool I36 positioned within the chamber 134 for sliding movement thereinbetween an upper and a lower location in chamber 134. The casing 132comprises a hollow cylindrical body 138 and a cap 140 sealed to a largeopen end 142 of the body 138.

The body 138 is T-shaped in cross section, and comprises a largercylindrical portion 144 and a smaller cylindrical portion 146 concentricwith the larger portion 144. For convenience of reference the casing 132will be referred to hereinafter in the specification and claims asthough it stood upright like a T; the top of the T being the top of thecasing and the bottom of the leg portion of the T being referred to asthe bottom of the casing 132 or the bottom of the relay 130. The bottom148 of the casing 132, i.e., the smaller end of the body 138, is closedexcept for an axial opening 150 in fluid communication with chamber 134.The body 138 is provided with a pressure port 152 through a sidewall 154of the smaller portion 146 and a vent port 153 through sidewall 154offset from port 152 toward the bottom 148 such that port 153 cannot bein fluid communication with a passageway 178 of spool 136. The body 138is also provided with a vent port 156 through a disc-shaped wall 158connecting the larger cylindrical portion 144 with the smallercylindrical portion 146 of the body 138.

The cap 140 is provided with an axially disposed port 160, which port160 tapers from a larger opening inside the relay 130 to a smalleropening 162 on the outside surface of cap 140.

The spool 136 is dimensioned to slidably fit within the chamber 134 insealing relationship with the walls defining chamber 134. The spool 136is also T-shaped in cross section and comprises a head portion 164 and aleg portion 166. The

spool 136 is provided with an axial passageway 168 extending through theentire length thereof from an opening 170 in the bottom surface 172 ofthe leg portion 166 to an opening 174 in the top surface 176 of the headportion 164. The axial passageway 168 converges or tapers down to asmaller diameter adjacent opening 174. The spool 136 also includes aradial passageway 178, extending radially through one side of the legportion 166 and is positioned so as to be in register with port 152 whenthe spool 136 is in its lowermost position in chamber 134, i.e., whenthe spool 136 is adjacent the bottom 148 of the casing 132. The spoolalso includes a circumferential groove 179 communicating with thepassageway 178 to ensure communication between passageway 178 and port152 regardless of the angular orientation of the spool 136. An upwardlyextending spacer lug 180 is connected to top surface 176 and extendsbetween the top surface 176 and the cap to prevent top surface 176 fromcoming into contact with cap 140, to provide a chamber 182 in which theactuating fluid (air) can act against top surface 176 to force the spool136 from its upper location (shown in FIG. 14) to its lower location,when opening 162 is blocked. In the lower location of the spool 136 inthe chamber 134, the bottom surface 172 of the leg portion 166 of thespool 136 is spaced from the bottom 148 of casing 132 (see spool 136 inFIG. 19). This provides a chamber or air space in which the air pressurecan act against the entire bottom surface of the spool to force thespool to its upper location in the chamber when the port 160 is open.The spool 136 also includes a relatively shallow and wide,circumferential groove 177 to provide fluid communication between ports152 and vent port 153 when the spool 136 is in the position shown inFIG. 14. When spool 136 is in the bottom of the chamber 134, the ventport 153 dead heads against the outside surface of the spool 136 at alocation below the groove 179.

The existence of the spool 136 in the chamber 134 effectively separatesthe entire chamber 134 into three separate volumes or chambers 182, 184and 186. Chamber 182 was described above. Chamber 184 is positionedbetween a bottom surface 188 of head portion 164 of the spool 136, andan upper surface 190 of the wall 158. Chamber 184 communicates withatmosphere through vent port 156. Chamber 186 is positioned between thebottom 170 of spool 136 and the bottom end 148 of the casing 132.Chamber 182 is in fluid communication with chamber 186 via passageway168. Chambers 182 and 186 are in communication with port 152 when thespool 136 is in its lowermost position in chamber 134.

The head portion 144 of the casing 132 includes means for mounting therelay 130 in an opening 192 in a panel 194, for example. The mountingmeans comprises a radial flange 196 and an annular groove 198 forreceiving a locking spring 200, such as a bowed E-ring.

A fluid pressure line 202 (schematically shown) is connected to port anda fluid pressure line 204 (schematically shown) is connected to port152. A vent line 205 (schemati' cally shown)is connected to vent port153.

The operation of the differential pressure relay 130 is as follows: Therelay 130 provides fluid communication between lines 202 and 204 whenport is closed. When the port 160 is open, lines 202 and 204 are not influid communication, although line 204 is in communication with ventline 205.

Referring to FIG. 14, air from line 202 enters the relay through port150, fills chamber 186, flows through passageway 168, enters chamber 182and exits through opening 160. The flow is balanced by means of thetapering port 160 and the taper in passageway 168 to opening 174, suchthat the pressure in chamber 186 is greater than that in chamber 182,whereby spool 136 is forced to its uppermost position (shown in FIG. 4).Now consider the case when port 160 is closed; closing of port 160 canbe accomplished, for example, by covering hole 162 with, for example,some movable element of the machine being controlled. When port 160 isclosed the air pressure in chamber 182 builds up until the force of theair pressure in chamber 182 is greater than that in chamber 186 andspool 136 is forced to its lowermost position in chamber 134, placingpassageway 178 in register with port 152. Air from line 202 now flowsout through line 204. When port 160 becomes unblocked, spool 136 willmove back to its uppermost position, interrupting the air flow into line204. Since chamber 184 is vented to atmosphere, the pressure thereinremains substantially constant. FIG. 19 illustrates one way in whichrelay 130 can be connected in a fluid logic control circuit.

Because the following four embodiments of the present invention employ acasing similar to casing 132 of the relay 130 described above, the samereference numerals (with a first prime, second prime, etc. for eachsubsequent embodiment) will be used where possible, for ease ofdescription and understanding.

MICRO-VALVE DIFFERENTIAL PRESSURE RELAY 210 FIG. shows a micro-valvedifferential pressure relay 210 which is a modification of thedifferential pressure relay 130 of FIG. 14 providing for the remotepositioning of the port 160. Relay 210 employs a cap 212 provided with acylindrical port 214 rather than an outwardly converging port. Amicrovalve 216 is connected to port 214 by a fluid pressure line 218.Micro-valve 216 comprises a main body 220 and a tube 222 and has apassageway 224 therethrough, converging at port 226 in tip 228 to asmall opening 230. This relay 210 has the added flexibility over relay130 of FIG. 14 in the ease and simplicity with which the control port226 can be positioned in the desired location. The operation of relay210 is identical to that of relay 130. FIG. 19 illustrates one way inwhich relay 210 can be used.

I invention which employs a casing 132" similar to that of the relay 130of FIG. 14, however the pilot light 240 employs a The spool 276comprises a knob 282, a head portion 284 and a leg portion 286. Knob 282extends through an opening 288 in cap 274. Opening 288 is larger thanthe outside diameter of knob 282, thus venting chamber 182" toatmosphere. The spool 276 has an axial passageway 290 extending partwaythrough the spool from an opening 292 in the bottom end 294 of the spool276, and a radial passageway 296 in communication with axial passageway290. Radial passageway 296 is axially located so as to be in registerwith one of the ports 278 and 280 when the spool 276 is in its uppermostposition in chamber 134'". The head 284 of the spool 276 is providedwith a key 298 which fits in one of the two circumferentiallyspaced-apart slots 300 and 302; key 298 and slots 300 and 302 positionpassageway 296 in register with ports 278 and 280 respectively.

Air input line 304 is connected to port 150'" and air output lines 306and 308 are connected to ports 278 and 280, respecdifferent cap 242 anda different spool 244. The cap 242 is solid and is transparent. Thespool 244 is identical to spool 136 except for the design of thepassageway 246. Passageway 246 terminates short of the bottom end 248 ofspool 244 such that passageway 246 is not in fluid communication withchamber 186". At the other end of the spool 244, passageway 246terminates in an opening 250 of the same diameter as the passageway 246;in this embodiment, there is no need for a converging port. Spool 244 isprovided with a radial aperture 252 in fluid communication with thepassageway 246. Radial passageway 252 is in register with the port 152"when spool 244 is in its uppermost position (shown in FIG. 16).

When spool 244 is adjacent the transparent cap 242, the spool 244 iseasily visible to the eye. The surface 256 of spool 244 can be paintedan easily visible color, such as red or black, such that the location ofthe spool 244 adjacent the cap 242 will be readily apparent. When thespool 244 is in its lowermost position in chamber 134" this fact willalso make itself readily known by merely glancing at the window or cap242.

The operation of the pilot light 240 is as follows: When air pressure isexerted through a line 258 connected to port 150 spool 244 is forced toits uppermost position (shown in FIG. 16). When fluid pressure isexerted through line 260, the force within chamber 182 and withinpassageway 24.6 is greater than that in chamber 186" and the spool 244is forced to its lowermost position adjacent end 148" of the casing132".

SELECTOR SWITCH 270 FIG. 17 shows a selector switch 270 embodiment ofthe present invention. The purpose of the selector switch 270 is toallow an operator, by manually turning a knob 282, to select which, ifany, of the air lines 306 and 308 is to be put in fluid communicationwith an air input line 304. The selector switch 270 employs a casing132" similar to casing 132 of the differential pressure relay 130 ofFIG. 14 except that the casing 132" employs a different cap 274, holds adifferent spool 276, and includes a plurality of circumferentiallyspaced-apart radial apertures 278 and 280.

tively. Knob 282 can be manually grasped and by pushing in and thenturning, the desired one of lines 306 and 308 can be placed in fluidcommunication with line 304. Since a certain amount of pressure isexerted in an upward direction (toward knob 282) by the air within thepassageway 290 and in chamber 186'", some downward (inward) force mustbe exerted on the knob 282 to unseat the key 298 from its slot 300 or302 before turning the spool 276 to the desired orientation. Indicia canbe provided on the outside of the knob 282 and the cap 274,corresponding to the various ports 278 and 280.

More than two ports can be circumferentially spaced around the casing,if desired, and additional slots can be provided in cap 274 to properlyorient the spool. Further, it may be desired to provide a slot to orientthe passageway 290 against a solid wall such that line 304 is closed.

It is to be understood that the switch 270 can also contain a second(and third, etc.) series of ports and a passageway, axially spaced fromthe series of ports and a passageway shown in the drawings, to perform aplurality of switching functions at the same time. Such a structure isshown in FIG.,19 which also shows one way of connecting the selectorswitch 270 of the present invention in a fluid logic control system.

PUSH BUTTON RELAY 310 FIG. 18 shows a push button relay 310 embodimentof the present invention. Push button relay 310 comprises a casing 132"having a chamber 134"", a spool 312 positioned in the chamber 134"" anda push button 314. The push button relay 310 is connected to two fluidpressure lines 316 and 320 and to a vent line 318. When the spool 312 isin the position shown in FIG. 18, fluid communication is establishedbetween pressure line 320 and vent line 318. By pushing in on pushbutton 314, such communication is interrupted and communication isprovided instead between pressure lines 316 and 320.

Referring now in detail to the structure of the push button relay 310,the casing 132" includes a vent port 156", an axial port 150"" in thebottom end 148"' of the casing 132"", and a pair of axially spaced-apartradial ports 322 and 324 extending through the sidewall 154"" of the legportion 146"" of casing 132". The spool 312 sealingly fits within thechamber 134"" and is adapted to move back and forth therein. The spool312 has an axial passageway 326 extending part way therethrough from'acountersunk opening 328 in the bottom end 330 thereof. The passageway326 is in fluid communication with a radial passageway 332 extendingentirely through one sidewall 334 of the leg portion 336 of spool 312.The spool 312 is provided with a circumferential groove 338 incommunication with passageway 332. The purpose of the groove 338 is toensure communication between lines 316 and 320, when the spool 312 is inits lower position, regardless of the angular orientation of the spool312. The passageway 332 is located such that it is in register with port324 when the Spool 312 is also provided with a relatively wide,relatively shallow, circumferential groove 341, wide enough to providefluid communication between ports 322 and 324, when the spool 312 is inthe position shown in FIG. 18.

The casing 132" includes a cap 340 having a central opening 342 thereinto accommodate the push button 314. The push button is retained with thecasing 132"" by means 'of a retaining flange 344. The opening 342 islarger than the outside diameter of the push button 314 to provide avent for chamber 182".

The push button 314 is adapted to slide axially through opening 342 suchthat when pushed in, it in turn pushes the spool 312 down to itslowermost position in chamber 134".

In operation, fluid pressure introduced through line 316 into chamber186" will force the spool 312 up to its uppermost position (shown inFIG. 18), in which position line 320 is in fluid communication with ventline 318 via groove 341. Communication between lines 320 and 318 isinterrupted by manually pushing in push button 314 causing spool 312 tooccupy itslowermost position providing fluid communication between lines320 and 316.

FLUID LOGIC CIRCUIT FIG. 19 shows a fluid logic control circuit usingfive of the above-described embodiments of the present invention,illustrating one example of how such embodiments can be combined tocontrol a machine operation. The machine operation in FIG. 19 is thereciprocating movement of a piston 350 inside of chamber 352 of cylinder354. The piston 350 is connected through a piston rod 356 to a body 358mounted on the opposite end of the rod 356. The ends of the chamber 352are defined by first and second end plates 360 and 362. The piston rod356. is supported for sliding movement through a cylindrical passageway364 in end plate 362. Each of the end plates 360 and 362 is providedwith a fluid passageway 366 and 368 respectively, connected to fluidlines 370 and 372, which lines are adapted to introduce air into thechamber 352, on one side or the other of piston 350. The fluid controlcircuit of FIG. 19 controls the reciprocating motion of the piston 350by alternately introducing air into chamber 352 through lines 370 and372.

The circuit includes an air pressure source 374, a multiple pole relay100 (see FIGS. -13), a selector switch 270 (see FIG. 17), a pilot light240 (see FIG. 16), a differential pressure relay 130 (see FIG. 14) and amicro-valve differential pressure relay 210 (see FIG. The relays 210 and130 are positioned to contact the body 358 at the left and right endpoints, respectively, of the travel of body 358, at which points body358 closes ports 226 and 160, respectively.

The air pressure source 374 is connected directly to the inlet port ofeach of the selector switch 270 and the differential pressure relays 210and 130 via lines 376, 378 and 380 respectively. In turn, the outputlines 382, 384, and 386 respectively, from the switch 270 and the relays210 and 130 are connected to the multiple pole relay 100, at ports B-3,30 and 28 respectively.

The output lines 384 and 386 from the differential pressure relays 210and 130 respectively, control the position of the spool 102 (see FIG.10) within the multiple pole relay 100, by virtue of being connected toports 30 and 28 respectively.

The output line 382 from the selector switch feeds air to one of the twopassageways 366 and 368 of the cylinder 354, via the multiple pole relay100. The manner in which the air flow is controlled to alternately feedair to the passageways 366 and 368 from line 382 (carrying air pressurefrom the source 374) is as follows: Output line 382 is connected to portB-3 of relay 100 and the feed lines 370 and 372 (to the cylinder 354)are connected to the ports B-2 and 34 respectively.

In the position of the piston 350 shown in FIG. 19, the body 358 hasbeen moving to the left and has just reached and closed the port 226 ofthe micro-valve 216, and has just forced spool 136 of relay 210 to itslower location, thus establishing fluid communication between lines 378and 384. Air pressure from line 384 enters port 30' of relay 100 forcingthe spool 102 (not shown see FIG. 12) to its leftmost location as viewedin FIG. 19. When spool 102 (not shown) reaches its leftmost location inrelay 100, fluid communication will be establishedbetween ports B3' andB'2'. Air pressure will then flow from source 374 through switch 270,through relay 100, through line 370, into passageway 366 and intochamber 352 forcing the piston 350 back to the right. At the same time,ports B'4 and B'-5 are in fluid communication whereby the air in chamber352 to the right of piston 350 is vented to atmosphere.

When body 358 reaches relay 130, relay 130 causes the spool 102 of relay100 to move to the right, resulting in air pressure being introducedinto chamber 352 through line 372 and passageway 368 in a similar mannerto that described above. Also, the air in chamber 352 to the left ofpiston 350 is now vented to atmosphere through port B'1 in relay 100.

In this way, the reciprocating motion of the piston 350 is controlledand maintained. Flow control valves 388 and 390 can be provided in lines370 and 372, respectively, to control the speed of air flow to thecylinder 354 and thus the speed of reciprocation.

In order to indicate to an operator, what the position of the piston 350is at any time, a pilot light 240 can be used as follows. The selectorswitch 270 is provided with a second outlet port 392, axially spacedfrom port 301. A line 394 is then connected between port 392 of switch270 and port C-3 of relay 100. Port 152" of'pilot light 240 is connectedto port C-2 of relay 100 via line 396. Port 150" of pilot light 240 isconnected to port C-4 of relay 100 via line 398. When the body 358reaches the position shown, the relay 210 forces spool 102 to the leftto provide fluid communication between lines 394 and 396 to force thespool 244 of the pilot light 240 from its upper to its lower location(FIG. 19 shows spool 244 after it has just moved to the lower location).At this time, air below spool 244 vents to atmosphere through port C'5in relay 100. When the piston 350 reaches the right side of cylinder 354as viewed in FIG. 19, spool 244 will be forced to its upper location,indicating through the transparent cap 242 the position of the piston350. At this time air above spool 244 vents to atmosphere through portC1' of relay 100.

The various air lines in all of the above embodiments are convenientlyplastic tubing, such as vinyl plastic. The tubing can be connected tothe ports of the various components by any known means, such as by brassfittings which are screwed into the ports. Other fluids than air can beused, such as nitrogen and various liquids, for example. The casings arepreferably injection molded of a plastic material such as Delrin, atrademark of duPont and the spools are preferably Gylon a trademark ofGarlock, Inc. for a fibrous filled fluorocarbon plastic. In all of theembodiments described above, the various spools are preferably made of aresilient material and are of a diameter (or of a width and thickness)slightly larger than the inside diameter of the chamber such that thespool is self-sealing in the chamber. Also it is preferred to use aplastic material of the type that is selflubricating; such materials arewell known. Other materials, such as metal, can be used with appropriatesealing means.

The invention has been described in detail with particular reference topreferred embodiments thereof, but it will be understood that variationsand modifications can be effected within the spirit and scope of theinvention as described hereinabove.

I claim 1. A fluid logic gate comprising: a. a casing having a chambertherein, said chamber being enclosed except for the hereinafter recitedfluid ports; b. a plurality of ports in said casing in fluidcommunication with said chamber; c. a pair of separate, unconnected,independently movable spools in said chamber, each spool beingpositioned for sliding movement in said chamber only between first andsecond locations, each spool always being in slidable contact with theother spool, each spool having a height substantially equal to theheight of said chamber and being in side-by-side sliding contact withthe other spool, each spool being completely contained within saidchamber, and each spool being slidable only in response to fluidpressure in said chamber; and

d. stop means fixedly positioned in said chamber contacting said spoolswhen said spools are in said second location.

2. The apparatus according to claim 1 wherein said plurality of spoolscomprises a pair of spools always in side-by-side slidable contact witheach other.

3. The apparatus according to claim 2 wherein each of said spoolsincludes at least one passageway for providing fluid communicationbetween predetermined ones of said ports.

4. The apparatus according to claim 3 including a fluid input signalline connected to at least one of said ports, a fluid output signal lineconnected to at least one of said ports, and fluid pressure linesconnected to said ports for moving said spools to their variouslocations in said chamber.

5. The apparatus according to claim 4 including fluid communicationmeans in said spools for providing fluid communication between saidinput and output signal lines when said spools are in a predeterminedlocation in said chamber.

6. The apparatus according to claim 2 wherein said'spools areself-sealing and self-lubricating in said chamber.

7. The apparatus according to claim wherein said spools are movabletogether and separately and when moved together are movable in the sameand in different directions.

8. A fluid logic gate for use in a fluid logic control systemcomprising:

a. a casing having an elongated chamber therein, said chamber beingenclosed except for the hereinafter recited fluid ports;

b. a plurality of ports in said casing in fluid communication with saidchamber;

. a pair of separate, unconnected spools movably positioned in saidchamber, each of said spools being independently movable between firstand second locations in said chamber, said spools being always inslidable, sideby-side contact with each other and being in sealingrelationship with each other and with the walls of said chamber, eachspool having a height substantially equal in fluid communication with afirst set of said ports when 5 in a first location and with a second setof said ports when in asecond location in said chamber; and

e. stop means fixedly positioned in said chamber contacting said spoolswhensaid spools are in said second location.

9. The apparatus according toclaim 8 wherein said spools are resilientand are self-sealing in said chamber.

10. The apparatus according to claim 8 wherein each of said spools ismovable between a first location adjacent a respective end wall of saidchamber toward a second location adjacent the center of said chamber,and including stop means contacting said spools at said secondlocations.

11. A fluid logic gate for use in a fluid logic control systemcomprising;

- a. a casing having a chamber therein;

b. a plurality of ports in said casing in fluid communication with saidchamber;

c. a pair of separate spools movably positioned in said chamber, each ofsaid spools being independently mova! ble between two differentlocations in said chamber, said spools being in sealing relationshipwith the walls of said e. wherein each of said spools is movablebetween'a first location adjacent a respective end wall of said chambertoward a second location adjacent the center of said chamber, andincluding stop means contacting said spools at said second locations;

f. wherein said casing includes a cover having certain of said portsarranged therein in a regular, rectangular array comprising a series ofrows and a series of columns;

g. wherein each of said spools is identical, is L-shaped, and ispositioned in reverse orientation to the other spool in said chamber;

h. wherein each spool has a single transverse groove in its uppersurface providing communication between two adjacent ports in the samecolumn and in adjacent rows; and

. wherein the width of an arm extension'of the L" of each spool issubstantially equal to the width of said chamber and is positionedadjacent the end of said chamber.

12. A fluid logic gate for use in a fluid logic control systemcomprising: I

a. a casing having an elongated chamber therein;

b. a plurality of ports in said casing in fluid communication with saidchamber;

c. a pair of separate, unconnected spools movably positioned in saidchamber, each of said spools being independently movable between twodifferent locations in said chamber, said spools being always inslidable, sideby-side contact with each other and being in sealingrelationship with each other and with the walls of said chamber;

d. each of said spools having at least one passageway therein in fluidcommunication with a first set of said ports when in a first locationand with a second set of said ports when in a second location in saidchamber; and wherein said plurality of ports includes:

e. a first fluid pressure input port through which fluid under pressurecan be introduced for moving one of said spools from its first to itssecond location in said chamber;

f. a second fluid pressure input port through which fluids underpressure can be introduced for moving the other of said spools from itsfirst to its second location in said chamber;

g. a third fluid pressure input port through which fluid under pressurecan be introduced in said chamber for simultaneously moving both of saidspools from their second location to their first location;

h. at least one fluid input signal port in communication with saidchamber; and

i. at least one fluid output signal port in communication with saidchamber.

13. The apparatus according to claim 12 including fluid pressure conduitmeans connected to certain of said ports for biasing said spools totheir first locations respectively.

14. The apparatus according to claim 13 wherein said passageways arelocated so as to provide fluid communication between said input signalport and said output signal port when said spools are in a predeterminedposition in said chamber.

' 15. The apparatus according to claim 13 including means providingfluid communication between said input and output signal ports only whenboth of said spools are in their second positions, whereby said gate canperform AND logic functions.

16. The apparatus according to claim 13 including means providing fluidcommunication between said input and output signal ports when at leastone of said spools is in its second position, whereby said gate canperform OR logic functions.

17. The apparatus according to claim 13 including means providing fluidcommunication between said input and output signal ports only whenneither of said spools is in its second location, whereby said gate canperform NOT logic functions.

18. The apparatus according to claim 13 including means providing fluidcommunication between said input and output signal ports when at leastone of said spools is in its first position, whereby said gate canperform NOR logic functions.

19. A fluid logic gate for use in a fluid logic control systemcomprising:

a. a casing having an elongated chamber therein;

a plurality of ports in said casing in fluid communication with saidchamber;

. a pair of separate, unconnected spools movably positioned in saidchamber, each of said spools being independently movable between twodifferent locations in said chamber, said spools being always inslidable, sideby-side contact with each other and being in sealingrelationship with each other and with the walls of said chamber;

. each of said spools having at least one passageway therein in fluidcommunication with a first set of said ports when in a first locationand with a second set of said ports when in a second location in saidchamber;

. a first fluid pressure input line connected to at least one of saidports for moving one of said spools from its first location to itssecond location in said chamber;

. a second fluid pressure input line connected to at least one of saidports for moving the other of said spools from its first to its secondlocation in said chamber;

a third fluid pressure input line connected to at least one of saidports for simultaneously moving both of said spools from their secondlocation to their first location;

. a fluid input signal line connected to at least one of said ports; and

i. a fluid output signal line connected to at least one of said ports.

20. A fluid operated device for use in a fluid logic control system forperforming any one of the four logic functions AND, OR, NOT, NOR,comprising:

a. a casing having a chamber therein, said chamber being enclosed exceptfor the hereinafter recited fluid ports;

b. a plurality of ports in said casing in fluid communication with saidchamber said plurality of ports including all of the ports necessary forsaid device to perform each one of said logic functions;

. a pair of separate, unconnected independently movable d. each of saidspools having at least one passageway for providing fluid communicationbetween predetermined ones of said ports;

e. fluid pressure lines connected to predetermined ones of said portsfor performing a predetermined one of said four logic functions, and

f. stop means fixedly positioned in said chamber contacting said spoolswhen said spools are in said second location.

1. A fluid logic gate comprising: a. a casing having a chamber therein,said chamber being enclosed except for the hereinafter recited fluidports; b. a plurality of ports in said casing in fluid communicationwith said chamber; c. a pair of separate, unconnected, independentlymovable spools in said chamber, each spool being positioned for slidingmovement in said chamber only between first and second locations, eachspool always being in slidable contact with the other spool, each spoolhaving a height substantially equal to the height of said chamber andbeing in side-by-side sliding contact with the other spool, each spoolbeing completely contained within said chamber, and each spool beingslidable only in response to fluid pressure in said chamber; and d. stopmeans fixedly positioned in said chamber contacting said spools whensaid spools are in said second location.
 2. The apparatus according toclaim 1 wherein said plurality of spools comprises a pair of spoolsalways in side-by-side slidable contact with each other.
 3. Theapparatus according to claim 2 wherein each of said spools includes atleast one passageway for providing fluid communication betweenpredetermined ones of said ports.
 4. The apparatus according to claim 3including a fluid input signal line connected to at least one of saidports, a fluid output signal line connected to at least one of saidports, and fluid pressure lines connected to said ports for moving saidspools to their various locations in said chamber.
 5. The apparatusaccording to claim 4 including fluid communication means in said spoolsfor providing fluid communication between said input and output signallines when said spools are in a predetermined location in said chamber.6. The apparatus according to claim 2 wherein said spools areself-sealing and self-lubricating in said chamber.
 7. The apparatusaccording to claim 2 wherein said spools are movable together andseparately and when moved together are movable in the same and indifferent directions.
 8. A fluid logic gate for use in a fluid logiccontrol system comprising: a. a casing having an elongated chambertherein, said chamber being enclosed except for the hereinafter recitedfluid ports; b. a plurality of ports in said casing in fluidcommunication with said chamber; c. a pair of separate, unconnectedspools movably positioned in said chamber, each of said spools beingindependently movable between first and second locations in saidchamber, said spools being always in slidable, side-by-side contact witheach other and being in sealing relationship with each other and withthe walls of said chamber, each spool having a height substantiallyequal to the height of said chamber, each spool being completelycontained within said chamber, and each spool being slidable only inresponse to fluid pressure in said chamber; d. each of said spoolshaving at least one passageway therein in fluid communication with afirst set of said ports when in a first location and with a second setof said ports when in a second location in said chamber; and e. stopmeans fixedly positioned in said chamber contacting said spools whensaid spools are in said second location.
 9. The apparatus according toclaim 8 wherein said spools are resilient and are self-sealing in saidchamber.
 10. The apparatus according to claim 8 wherein each of saidspools is movable between a first location adjacent a respective endwall of said chamber toward a second location adjacent the center ofsaid chamber, and including stop means contacting said spools at saidsecond locations.
 11. A fluid logic gate for use in a fluid logiccontrol system comprising: a. a casing having a chamber therein; b. aplurality of ports in said casing in fluid communication with saidchamber; c. a pair of separate spools movably positioned in saidchamber, each of said spools being independently movable between twodifferent locations in said chamber, said spools being in sealingrelationship with the walls of said chamber; d. each of said spoolshaving at least one passageway therein in fluid communication with afirst set of said ports when in a first location and with a second setof said ports when in a second location in said chamber; e. wherein eachof said spools is movable between a first location adjacent a respectiveend wall of said chamber toward a second location adjacent the center ofsaid chamber, and including stop means contacting said spools at saidsecond locations; f. wherein said casing includes a cover having certainof said ports arranged therein in a regular, rectangular arraycomprising a series of rows and a series of columns; g. wherein each ofsaid spools is idEntical, is L-shaped, and is positioned in reverseorientation to the other spool in said chamber; h. wherein each spoolhas a single transverse groove in its upper surface providingcommunication between two adjacent ports in the same column and inadjacent rows; and i. wherein the width of an arm extension of the''''L'''' of each spool is substantially equal to the width of saidchamber and is positioned adjacent the end of said chamber.
 12. A fluidlogic gate for use in a fluid logic control system comprising: a. acasing having an elongated chamber therein; b. a plurality of ports insaid casing in fluid communication with said chamber; c. a pair ofseparate, unconnected spools movably positioned in said chamber, each ofsaid spools being independently movable between two different locationsin said chamber, said spools being always in slidable, side-by-sidecontact with each other and being in sealing relationship with eachother and with the walls of said chamber; d. each of said spools havingat least one passageway therein in fluid communication with a first setof said ports when in a first location and with a second set of saidports when in a second location in said chamber; and wherein saidplurality of ports includes: e. a first fluid pressure input portthrough which fluid under pressure can be introduced for moving one ofsaid spools from its first to its second location in said chamber; f. asecond fluid pressure input port through which fluids under pressure canbe introduced for moving the other of said spools from its first to itssecond location in said chamber; g. a third fluid pressure input portthrough which fluid under pressure can be introduced in said chamber forsimultaneously moving both of said spools from their second location totheir first location; h. at least one fluid input signal port incommunication with said chamber; and i. at least one fluid output signalport in communication with said chamber.
 13. The apparatus according toclaim 12 including fluid pressure conduit means connected to certain ofsaid ports for biasing said spools to their first locationsrespectively.
 14. The apparatus according to claim 13 wherein saidpassageways are located so as to provide fluid communication betweensaid input signal port and said output signal port when said spools arein a predetermined position in said chamber.
 15. The apparatus accordingto claim 13 including means providing fluid communication between saidinput and output signal ports only when both of said spools are in theirsecond positions, whereby said gate can perform AND logic functions. 16.The apparatus according to claim 13 including means providing fluidcommunication between said input and output signal ports when at leastone of said spools is in its second position, whereby said gate canperform OR logic functions.
 17. The apparatus according to claim 13including means providing fluid communication between said input andoutput signal ports only when neither of said spools is in its secondlocation, whereby said gate can perform NOT logic functions.
 18. Theapparatus according to claim 13 including means providing fluidcommunication between said input and output signal ports when at leastone of said spools is in its first position, whereby said gate canperform NOR logic functions.
 19. A fluid logic gate for use in a fluidlogic control system comprising: a. a casing having an elongated chambertherein; b. a plurality of ports in said casing in fluid communicationwith said chamber; c. a pair of separate, unconnected spools movablypositioned in said chamber, each of said spools being independentlymovable between two different locations in said chamber, said spoolsbeing always in slidable, side-by-side contact with each other and beingin sealing relationship with each other and with the walls of saidchamber; d. each of said spools having at least one passageway thereinin fluid communication with a first set of said ports when in a firstlocation and with a second set of said ports when in a second locationin said chamber; e. a first fluid pressure input line connected to atleast one of said ports for moving one of said spools from its firstlocation to its second location in said chamber; f. a second fluidpressure input line connected to at least one of said ports for movingthe other of said spools from its first to its second location in saidchamber; g. a third fluid pressure input line connected to at least oneof said ports for simultaneously moving both of said spools from theirsecond location to their first location; h. a fluid input signal lineconnected to at least one of said ports; and i. a fluid output signalline connected to at least one of said ports.
 20. A fluid operateddevice for use in a fluid logic control system for performing any one ofthe four logic functions AND, OR, NOT, NOR, comprising: a. a casinghaving a chamber therein, said chamber being enclosed except for thehereinafter recited fluid ports; b. a plurality of ports in said casingin fluid communication with said chamber said plurality of portsincluding all of the ports necessary for said device to perform each oneof said logic functions; c. a pair of separate, unconnectedindependently movable spools in said chamber, each spool beingpositioned for sliding movement in said chamber only between first andsecond locations, said spools being always in slidable contact with eachother, each spool having a height substantially equal to the height ofsaid chamber and being in side-by-side sliding contact with the otherspool, each spool being completely contained within said chamber, andeach spool being slidable only in response to fluid pressure in saidchamber; d. each of said spools having at least one passageway forproviding fluid communication between predetermined ones of said ports;e. fluid pressure lines connected to predetermined ones of said portsfor performing a predetermined one of said four logic functions, and f.stop means fixedly positioned in said chamber contacting said spoolswhen said spools are in said second location.